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Hydrothermal formation of W/Mo-oxides: A multidisciplinary study of growth and shape


Kiebach, R; Pienack, N; Bensch, W; Grunwaldt, J D; Michailovski, A; Baiker, A; Fox, T; Zhou, Y; Patzke, Greta R (2008). Hydrothermal formation of W/Mo-oxides: A multidisciplinary study of growth and shape. Chemistry of Materials, 20(9):3022-3033.

Abstract

The hydrothermal formation of mixed nanoscale W/Mo-oxides with the hexagonal tungsten bronze (HTB) structure has been investigated by in situ EDXRD (energy dispersive X-ray diffraction). Compared to the binary oxide systems, they display intermediate kinetics with a nucleation-controlled mechanism dominated by the slow growing tungsten component. Furthermore, the thermal stability of nanostructured W/Mo-HTB compounds has been monitored through combined in situ X-ray absorption spectroscopy (XAS) and XRD in reducing and oxidizing atmospheres. Their transformation into other mixed nanostructures was only observed above 300 °C in O2- and H2-containing atmospheres. In addition, the shape of nanoscale hexagonal W/Mo-oxides can be expanded into a variety of morphologies via the use of alkali chlorides as hydrothermal additives. The alkali cations exert a two-fold role as internal stabilizers and external shape control agents. Their mobility within the channels of the W/Mo-oxide host framework has been investigated by solid state NMR spectroscopy.

Abstract

The hydrothermal formation of mixed nanoscale W/Mo-oxides with the hexagonal tungsten bronze (HTB) structure has been investigated by in situ EDXRD (energy dispersive X-ray diffraction). Compared to the binary oxide systems, they display intermediate kinetics with a nucleation-controlled mechanism dominated by the slow growing tungsten component. Furthermore, the thermal stability of nanostructured W/Mo-HTB compounds has been monitored through combined in situ X-ray absorption spectroscopy (XAS) and XRD in reducing and oxidizing atmospheres. Their transformation into other mixed nanostructures was only observed above 300 °C in O2- and H2-containing atmospheres. In addition, the shape of nanoscale hexagonal W/Mo-oxides can be expanded into a variety of morphologies via the use of alkali chlorides as hydrothermal additives. The alkali cations exert a two-fold role as internal stabilizers and external shape control agents. Their mobility within the channels of the W/Mo-oxide host framework has been investigated by solid state NMR spectroscopy.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:English
Date:2008
Deposited On:21 Feb 2009 19:10
Last Modified:06 Dec 2017 18:23
Publisher:American Chemical Society
ISSN:0897-4756
Publisher DOI:https://doi.org/10.1021/cm7028036

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